Seems like they had a gimmick of "big-bump pregnant super-heroine fights crime!" and then wimped out of really making it a thing because too many readers were saying: "Oh no, that could harm the baby." (Baby, meanwhile, once born, contributes nothing to the plot other than 'side-character babysits it when the heroine actually needs to do something.')

A lot of people claim that pregnant Spider Woman was a dumb gimmick of "Pregnant and fighting crime" but that never actually happened in the book. While there is reference to her trying that, all 4 issues of her pregnancy were just her reluctantly stopping a hostage situation that she was a part of. Plus this does affect her character as a new motovation and reason to be both softer and harsher to people. This may have been a silly idea but it was executed well.

The Authority, Volume 1 issue 13: When evacuating the human race to alternate realities (the earth is trying to kill humanity off- long story) one of the parallel worlds is a classic genderbent universe in which the team leader's female counterpart is six momths pregnant.